How odd it was to glance at the latest contribution in Comment is free's series on Free Speech and the Internet to discover that the Muslim Council of Britain's Inayat Bunglawala has used his piece to defend the banned jihadist group, al-Muhajiroun, by attacking me.

Inayat's gripe is that I called for the man who runs al-Muhajiroun – an old university friend of mine called Anjem Choudhury – to be arrested.

How unsurprising it is to find that Mr Bunglawala – a man who circulated the writings of the "freedom fighter" Osama bin Laden a few months before 9/11 and who called the jihadist ideologue Sheikh Omar Abdul Rahman "courageous" – rushing to the defence of the jihadists of al-Muhajiroun. Inayat hasn't really changed his tune. Instead of praising jihadists, wants now us to believe that active advocates of terrorism against this country like Anjem Choudhury are no more than "loudmouth tabloid favourites". He would like you to take his word that there is no connection between the murderous jihadist plots that are presently clogging up our courts, and the explicit theological incitement to terrorism that has been pumped out by the British jihadist groups for nearly two decades.

I am a huge supporter of freedom of expression. It has been very useful to see the likes of Inayat Bunglawala speak their brains. We now have had a very good chance to see the minds of Britain's most active Islamists in action. I don't think they've done themselves any favours, frankly. There is nothing more amusing that the spectacle of Inayat twisting and turning, trying to avoid tripping himself up. He rarely succeeds, but it is fun to watch him do his best.

Were it not for freedom of expression, I wouldn't have been able to publish the internal documents – leaked to me by an insider – on Harry's Place that show Inayat Bunglawala's game plan for rebranding his Islamist politics, by means of his ENGAGE project. Were it not for freedom of expression, I would not be able to point out the stupidity of calling his thinktank by the very same name used by the anti-racist, pro-two states campaign group Engage.

There are downsides to freedom of expression, of course. Inayat knows very well that I have very grave reservations about the outrageous state of the English law of defamation, and would therefore, as a matter of principle, be very reluctant to sue a person who libels me. That's the price you pay for freedom of expression. Accordingly, Inayat linked to an article that grossly defames me, knowing that he ran little risk of me suing him. Without my asking, the Guardian removed that defamatory link. However, I did think it unfair for him to take advantage of my fondness for freedom of speech in this manner.

There are certainly limits to freedom of expression. The right of one man to incite another to kill is not protected free speech. That is particularly so, where the man doing the inciting claims to exercise religious authority, and where that authority is accepted by the person who is being encouraged to kill. That is why I support the banning of religious groups that preach violent jihad.

In relation to my call to arrest those who are presently running al-Muhajiroun, Inayat states "it is not entirely clear what crime Choudhury is meant to have committed." Let me help him out. In 2006, the government banned al-Ghurabaa and The Saved Sect, which is what al-Muhajiroun at that time called itself. They're on the list of proscribed terrorist organisations. There is no difference between the personnel, the organisation, or the message of those groups, and "Islam4UK". Indeed, the site gives Choudhury and Omar Bakri Mohammed's phone numbers as contacts. There is no legal reason that Choudhury should not be arrested. He ought to be. I hope that he soon is.

None of this is of any concern to Inayat Bungalawala, of course. He'd rather spend the rest of his column attacking Jewish journalists. But then, that's what Inayat Bungalawa has done, since his stint editing the pro-Islamic Republic of Iran, pro-Hamas Trends magazine, where he obsessed extensively about Jews:

"The chairman of Carlton Communications is Michael Green of the Tribe of Judah. He has joined an elite club whose members include fellow Jews Michael Grade and Alan Yentob ... [They are] close friends … so that's what they mean by a 'free media'."

But here's the beauty of freedom of expression. If I weren't able to publish all this material on Inayat Bunglawala, then it is possible that he would not be recognised as – in the words of Christopher Hitchens – the sinister and preposterous figure that most sensible people know him to be. He might, even now, be helping to formulate government policy on anti-extremism, instead of writing blathering articles on Comment is free.